object Member {
  def main(args: Array[String]): Unit = {
    var members = Set("张三", "李四", "王五")
    members += "李四"
    members += "赵六"
    println("志愿者社团成员：")
    for (member <- members) {
      println("- " + member)
    }
    val hasZhangsan = members.contains("张三")
    println(s"是否有张三？$hasZhangsan")
    println(s"实际成员数：${members.size}")
  }
}